CHAPTER VI 



THE INTERNAL SECRETIONS OF THE 

 ORGANS OF REPRODUCTION 



We may now consider another role played by the essential 

 organs of reproduction, namely, that of elaborating chemical 

 substances and secreting them, not externally by ducts or canals, 

 but internally into the blood, where they are carried throughout 

 the whole body and act both on the general metabolism and 

 on a number of organs and structures which are thereby stimu- 

 lated in a variety of ways. The earliest evidence that the testes 

 and ovaries act in such a manner was that derived from the 

 effects of castration, an operation practised upon man and also 

 upon the domestic animals from primitive times. The results 

 of testicular and ovarian deprivation are referred to many times 

 in the works of Aristotle, but there is little doubt that the opera- 

 tion was practised before the dawn of history. The purpose 

 of castration as applied to man was to obtain de-sexed individuals 

 or eunuchs, usually for attendance upon women, as is still done in 

 oriental countries. With animals, the operation was carried out 

 for economic purposes, as it is to-day, it having been long 

 recognised that castrated animals fatten faster and more readily, 

 besides being more docile and easier to manage than entire ones. 

 For a similar reason ovariotomy or the removal of the ovaries 

 (the term castration being often restricted to the operation of 

 extirpation of the testes) was practised in quite early times on 

 sows, as recorded by Aristotle, but was not usually done on 

 other animals owing no doubt chiefly to the greater difficulty 

 of performing it. 



The general effect of castration in all vertebrate animals 

 is to prevent the development of the secondary sexual characters, 

 that is, of those characters which, wdiile correlated with the sex 

 in question, are not directly concerned with the reproductive 

 processes. This statement applies to ovariotomy as well as 



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